The original research proposal was to characterize chemically and biologically the L-arabinose binding protein (ABP) as a component of the "high affinity" uptake system in E. coli B/r, and to pursue a characterization of the "low affinity" uptake system designated araE. Crystalline ABP has been characterized with respect to amino acid composition and peptide mapped. CD spectra, ORD spectra and sedimentation velocity coefficients determined in presence and absence of L-arabinose indicate no gross structural changes occur when ligand is bound. Fluorescence spectroscopy and N-bromosuccinimide titrations indicate that the environment of some tryptophan residues is changed when ligand is bound. The galactose binding protein has crystallized and characterized to the same extent for comparative purposes. Immunological cross reactivity has been observed between antisera directed against either the GBP or the ABP and the heterologous protein, suggesting that although these are two distinctly different proteins they have some structural relationship. A biological relationship has been observed with respect to inducer specificities. ABP has been tentatively mapped at 39 min on the E. coli chromosome map. Detailed mapping is in progress. Characterization of the araE gene product is in progress but still in the preliminary stage.